Magnetodielectric effect and optic soft mode behaviour in quantum paraelectric EuTiO3 ceramics

TL;DR

This study investigates the magnetodielectric properties and optic soft mode behavior in EuTiO3 ceramics, revealing a soft phonon responsible for quantum paraelectricity and magnetic field effects on permittivity.

Contribution

It provides the first detailed analysis of the soft phonon and magnetodielectric effects in EuTiO3 ceramics, highlighting differences from single crystals.

Findings

Identified a polar optic phonon responsible for quantum paraelectricity.

Confirmed magnetic field dependence of permittivity in EuTiO3 ceramics.

Observed soft phonon behavior consistent with quantum paraelectric state.

Abstract

Infrared reflectivity and time-domain terahertz transmission spectra of EuTiO3 ceramics revealed a polar optic phonon at 6 - 300K, whose softening is fully responsible for the recently observed quantum paraelectric behaviour. Even if our EuTiO3 ceramics show lower permittivity than the single crystal due to a reduced density and/or small amount of secondary pyrochlore Eu2Ti2O7 phase, we confirmed the magnetic field dependence of the permittivity, also slightly smaller than in single crystal. Attempt to reveal the soft phonon dependence at 1.8K on the magnetic field up to 13T remained below the accuracy of our infrared reflectivity experiment.